The subject matter disclosed herein relates to a transmission assembly and, more particularly, to a multiple speed transmission for use with an aircraft accessory drive.
To improve aircraft turbine engine efficiency and fuel burn, manufacturers have attempted to increase turbine engine bypass ratios. Engines having increased turbine engine bypass ratios, however, often have high, intermediate and low pressure turbine sections with limited power extraction capability from the high pressure section. As such, manufacturers are interested in extracting power from the low pressure section.
A problem with power extraction from a turbine engine low pressure section is that the speed range over which the low pressure section operates has a speed ratio of about 5:1 vs. a 2:1 ratio for a typical turbine engine high pressure section. Until now, it has been difficult to use this extended speed range as an input to a variable frequency generator, which produces constant frequency or narrow band variable frequency (360-800 Hz) electric power.